Field of the Invention
The present invention relates to a coaxial connector. In particular, the present invention relates to a coaxial connector which is fixed to an end of a coaxial cable, and which can be electrically connected to a mating coaxial connector mounted to a printed circuit board, and to a structure of a coaxial connector which requires measures against EMI (Electro Magnetic Interference).
Related Art
For example, a coaxial connector is constituted of a coaxial plug attached to an end of a coaxial cable, and a receptacle mounted to a printed circuit board. By connecting the coaxial plug to the receptacle, it is possible to transmit a high frequency signal from the coaxial cable to the printed circuit board, or to transmit a high frequency signal from the printed circuit board to the coaxial cable.
Generally, a coaxial cable is constituted of a circular central conductor, a dielectric such as a fluorine-based resin or the like surrounding the perimeter of the central conductor, an outer conductor such as a braided wire or the like surrounding the perimeter of the dielectric, and an insulation sheath which covers and protects the outer conductor.
For example, the coaxial plug according to Japanese Unexamined Patent Application, First Publication No. 2006-339021 (below referred to as Patent Document 1), is provided with a cylindrical external contact, a rectangular tube-shaped external housing, and a concave retainer.
The housing has a contact receiving chamber opened at one side face, and an external contact furnished with a coaxial cable can be inserted into the contact receiving chamber. The end portion of the external contact inserted into this contact receiving chamber has a constitution such that, at one end portion the insulation sheath and the outer conductor of the coaxial cable are crimped, and in addition at the other end portion, a cylindrical insulating member into which the central conductor of the coaxial cable is inserted is crimped from an external circumferential direction thereof.
In the coaxial plug according to Patent Document 1, the rectangular tube-shaped housing cannot be made small, and therefore it is not easy to miniaturize the receptacle. Namely, there is the deficiency that lowering the implementation height of the receptacle, namely height reduction, is not easy. In response to this deficiency, for example, Japanese Unexamined Patent Application, First Publication No. 2013-258108 (below referred to as Patent Document 2) discloses a coaxial receptacle where a height reduction of the receptacle is easy.
In the coaxial connector according to Patent Document 2, the shell covering the internal housing of the contact connecting portion of the coaxial cable is fit to the external housing. This shell has an end portion which projects from the external housing, and which is inserted and connected to the receptacle. A lock piece is provided at an end portion of this shell, and the connection with the receptacle is locked. Further, a lock release lever is provided at the upper face of the external housing, so as to interlock with the above mentioned lock piece of the above mentioned shell fit to the external housing. Namely, by a pushing operation of the lock release lever, the lock piece is deformed, and the locking of the coaxial connector and the receptacle in the connected state is released.
In the above described constitution of the coaxial connector according to Patent Document 2, because of the range of motion of the lock piece of the shell, a pair of slits is cut into a side portion of the lock piece. Therefore, there is concern that a noise signal from the contact may leak through these slits. Also, there is concern that a noise signal may be input to the contact through these slits. The present invention was made in consideration of such problems, and has the objective of providing a coaxial connector provided with measures against EMI, while maintaining compatibility with coaxial connectors of the prior art.